Azulenesquaric acid dyes, azulene intermediates therefor, and optical recording medium

ABSTRACT

Azulenesquaric acid dyes of the formula ##STR1## where R 1 , R 2 , R 3 , R 4  and R 5  each have specified meanings are prepared from azulene derivatives of the formula ##STR2## where R 1 , R 2 , R 3 , R 4  and R 5  each have specified meanings as intermediates, and used in an optical recording medium.

The present invention relates to novel azulenesquaric acid dyes having aparticular substitution pattern, novel azulenes as intermediatestherefor, and a novel optical recording medium containing the novelazulenesquaric acid dyes.

Economical manufacture of optical data recording media requires dyeshaving particular properties. These dyes should have

a strong absorption between 700 and 900 nm in order to provide layerswritable with semiconductor lasers,

a high reflectivity in the layer in the near infrared (700-900 nm) inorder to require only a simple layer structure (without reflectorlayer),

high solubility, for example in order to be able to apply the thinstorage layer to a base material by spincoating, and

a high stability in thin layers.

All prior art storage materials have appreciable defects in at least oneof the requirements mentioned.

It is an object of the present invention to provide new dyes where theabovementioned defects do not occur at all or at most only to anextremely small extent.

We have found that this object is achieved with a novel azulenesquaricacid dye of the formula I ##STR3## where R¹ is C₁ -C₁₂ -alkyl, which maybe substituted by halogen, amino, hydroxyl, C₁ -C₁₂ -alkoxy, phenyl,substituted phenyl, carboxyl, C₁ -C₁₂ -alkoxycarbonyl, C₁ -C₁₂-haloalkoxycarbonyl, C₁ -C₁₂ -phenylalkoxycarbonyl, cyano, C₁ -C₁₂-alkanoyloxy, benzoyloxy, substituted benzoyloxy and/or by the radical##STR4## where R⁶ and R⁷ are identical or different and each is C₁ -C₄-alkyl or phenyl independently of the other, carboxyl, C₁ -C₁₂-alkoxycarbonyl, where the alkyl chain may be interrupted by one or moreoxygen atoms, carbamoyl or C₁ -C₄ -monoalkyl- or -dialkylcarbamoyl and

R², R³, R⁴ and R⁵ are identical or different and each is hydrogen or C₁-C₁₂ -alkyl, which may be substituted by halogen, amino, C₁ -C₁₂-alkoxy, phenyl, substituted phenyl, carboxyl, C₁ -C₁₂ -alkoxycarbonylor cyano, independently of the others,

with the proviso that, when R⁵ is hydrogen, the positions ofsubstituents CH₂ -R¹ and R⁴ on either or both azulene rings may also beinterchanged within an azulene ring and that R¹ is also hydrogen when R⁵is methyl or ethyl which may each be substituted by phenyl orsubstituted phenyl, or is C₃ -C₁₂ -alkyl or when at least one of the tworadicals R² and R⁴ is phenyl or substituted phenyl.

All the alkyl groups appearing in the compounds according to theinvention may be not only straight-chain but also branched.

If substituted phenyl groups appear in the compounds according to theinvention, suitable substituents are for example C₁ -C₄ -alkyl, C₁ -C₄-alkoxy, C₁ -C₄ -dialkylamino, N-phenyl-N-(C₁ -C₄ -alkyl)amino orhalogen.

If alkyl groups interrupted by oxygen atoms appear in the compoundsaccording to the invention, preference is given to those alkyl groupswhich are interrupted by from 1 to 3 oxygen atoms.

Halogen is in each case preferably fluorine, chlorine, or bromine.

The radicals R¹, R², R³, R⁴ and R⁵ in the formula I are for example,methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl,tert-butyl, pentyl, isopentyl, neopentyl, tert-pentyl, 2-methylbutyl,hexyl, 2-methylpentyl, isohexyl, heptyl, octyl, 2-ethylhexyl, nonyl,decyl, undecyl, dodecyl, fluoromethyl, chloromethyl, difluoromethyl,trifluoromethyl, trichloromethyl, 2-fluoroethyl, 2-chloroethyl,2-bromoethyl, 1,1,1-trifluoroethyl, heptafluoropropyl, 4-chlorobutyl,5-fluoropentyl, 6-chlorohexyl, cyanomethyl, 2-cyanoethyl, 3-cyanopropyl,2-cyanobutyl, 4-cyanobutyl, 5-cyanopentyl, 6-cyanohexyl, 2-aminoethyl,2-aminopropyl, 3-aminopropyl, 2-aminobutyl, 4-aminobutyl, 5-aminopentyl,6-aminohexyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl,2-hydroxybutyl, 4-hydroxybutyl, 5-hydroxypentyl, 6-hydroxyhexyl,2-methoxyethyl, 2-ethoxyethyl, 2-propoxyethyl, 2-isopropoxyethyl,2-butoxyethyl, 2-methoxypropyl, 2-ethoxypropyl, 3-ethoxypropyl,4-ethoxybutyl, 4-isopropoxybutyl, 5-ethoxypentyl, 6-methoxyhexyl,benzyl, 1-phenylethyl, 2-phenylethyl, 4-chlorobenzyl, 4-methoxybenzyl,2-(4-methylphenyl)ethyl, carboxymethyl, 2 -carboxyethyl,3-carboxypropyl, 4-carboxybutyl, 5-carboxypentyl, 6-carboxyhexyl,methoxycarbonylmethyl, ethoxycarbonylmethyl, 2-methoxycarbonylethyl,2-ethoxycarbonylethyl, 3-methoxycarbonylpropyl, 3-ethoxycarbonylpropyl,4-methoxycarbonylbutyl, 4-ethoxycarbonylbutyl, 5-methoxycarbonylpentyl,5-ethoxycarbonylpentyl, 6-methoxycarbonylhexyl or 6-ethoxycarbonylhexyl.

R² and R⁴ are each also for example 4-methylphenyl, 4-methoxyphenyl or4-chlorophenyl.

R¹ in the formula I is also for example methoxycarbonyl, ethoxycarbonyl,propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl,secbutoxycarbonyl, tert-butoxycarbonyl, pentyloxycarbonyl,isopentyloxycarbonyl, neopentyloxycarbonyl, tert-pentyloxycarbonyl,hexyloxycarbonyl, isohexyloxycarbonyl, heptyloxycarbonyl,octyloxycarbonyl, isooctyloxycarbonyl, nonyloxycarbonyl,isononyloxycarbonyl, decyloxycarbonyl, isodecyloxycarbonyl,undecyloxycarbonyl, dodecyloxycarbonyl (the designations isooctyl,isononyl and isodecyl are trivial names derived from oxosynthesisalcohols; cf. Ullmann's Encyklopadie der Technischen Chemie, 4thEdition, Volume 7, pages 215 to 217, and also Volume 11, pages 435 and436), 2-methoxyethoxycarbonyl, 2-ethoxyethoxycarbonyl,3,6-dioxaheptyloxycarbonyl, 1-methoxycarbonylethyl,1-ethoxycarbonylethyl, 1-propoxycarbonylethyl,1-isopropoxycarbonylethyl, 1-butoxycarbonylethyl,1-isobutoxycarbonylethyl, 1-sec-butoxycarbonylethyl,1-methoxycarbonylpropyl, 1-ethoxycarbonylpropyl,1-propoxycarbonylpropyl, 1-isopropoxycarbonylpropyl,1-butoxycarbonylpropyl, 1-isobutoxycarbonylpropyl,1-sec-butoxycarbonylpropyl, ∝-(methoxycarbonyl)benzyl,∝-(ethoxycarbonyl)benzyl, acetyloxymethyl, 2-acetyloxyethyl,2-(2,2-dimethylpropionyloxy)ethyl, 2-decanoyloxyethyl, benzoyloxymethyl,2-benzyloxyethyl, 2-(3,5-dimethoxy-4-methylbenzoyloxy)ethyl,2-(dimethylphosphinato)ethyl, 2-(diethylphosphinato)ethyl,2-(methyl-ethylphosphinato)ethyl,3-ethyl-2-(methyl-ethylphosphinato)propyl or2-(diphenylphosphinato)ethyl.

Preference is given to azulenesquaric acid dyes of the formula I whereR², R³, R⁴ and R⁵ are each C₁ -C₆ alkyl and R¹ is as defined above.

Particular preference is given to azulenesquaric acid dyes of theformula I where R² and R⁴ are each methyl, R³ and R⁵ are each hydrogen,and R¹ is as defined above. These dyes conform to the formula Ia##STR5##

Very particular preference is given to azulenesquaric dyes of theformula I where R² and R⁴ are each hydrogen, R³ is isopropyl, R⁵ ismethyl and R¹ is as defined above. These dyes conform to the formula Ib##STR6##

Preference is further given to azulenesquaric acid dyes of the formula Iwhere R¹ is C₁ -C₁₂ -alkyl which is substituted by C₁ -C₁₂-alkoxycarbonyl. Particularly noteworthy are those azulenesquaric aciddyes of the formula I where R¹ is C₁ -C₁₂ -alkoxycarbonylmethyl.

The dyes of the formula I are obtained from azulene derivatives of theformula II, where R¹, R², R³, R⁴ and R⁵ are each as defined above, byreaction with squaric acid of the formula III in accordance with thefollowing equation: ##STR7##

In the case of those azulene derivatives of the formula II where R⁵ ishydrogen, the link to the squaric acid can form at different ringpositions on the five-membered ring and give rise to isomeric productswhere, as stated above, the ring positions of the substituents CH₂ -R¹and R⁴ are interchanged. This is because compounds where the bond to thesquaric acid is formed on that side where the substituent CH₂ -R¹ isbonded must then be distinguished from those compounds where the bond tothe squaric acid is formed on that side where the substituent R⁴ isbonded. These isomeric compounds can be separated chromatographically.For application in storage layers, however, it is customary to use theisomeric mixtures.

The method of preparation is known per se and described for example inAngew. Chem. 78 (1966), 937.

In the reaction of squaric acid with azulene derivatives of the formulaII where R¹ is C₁ -C₁₂ -alkyl which is substituted by hydroxyl, inparticular in the case of the corresponding C₂ -C₃ -hydroxyalkylderivatives, it has been found that increasingly a cyclized 1:1 adductof azulene derivative and squaric acid forms as a byproduct.

The present invention further relates to a novel azulene derivative ofthe formula II ##STR8## where R¹ is C₂ -C₁₂ -alkyl, which may besubstituted by halogen, amino, hydroxyl, C₁ -C₁₂ -alkoxy, phenyl,substituted phenyl, C₁ -C₁₂ -alkoxycarbonyl, C₁ -C₁₂-haloalkoxycarbonyl, C₁ -C₁₂ -phenylalkoxycarbonyl, cyano, C₁ -C₁₂-alkanoyloxy, benzoyloxy, substituted benzoyloxy and/or by the radical##STR9## where R⁶ and R⁷ are identical or different and each is C₁ -C₄-alkyl or phenyl independently of the other, carboxyl, C₁ -C₁₂-alkoxycarbonyl, where the alkyl chain may be interrupted by one or moreoxygen atoms, carbamoyl or C₁ -C₄ -monoalkyl- and -dialkylcarbamoyl and

R², R³, R⁴ and R⁵ are identical or different and each is hydrogen or C₁-C₁₂ -alkyl which may be substituted by halogen, amino, C₁ -C₁₂ -alkoxy,phenyl, substituted phenyl, carboxyl, C₁ -C₁₂ -alkoxycarbonyl or cyano,independently of the others,

with the proviso that R¹ is also hydrogen when R⁵ is methylor ethylwhich are each substituted by phenyl or substituted phenyl, or C₃ -C₁₂-alkyl, or when at least one of the two radicals R² and R⁴ is phenyl orsubstituted phenyl.

Concerning a list of examples of the substituents R¹, R², R³, R⁴ and R⁵,reference is made to the preceding observations.

Particular preference is given to azulene derivatives of the formula IIwhere R² and R⁴ are each methyl, R³ and R⁵ are each hydrogen and R¹ isas defined above.

Very particular preference is given to azulene derivatives of theformula II where R² and R⁴ are each hydrogen, R³ is isopropyl, R⁵ ismethyl and R¹ is as defined above.

Preference is further given to azulene derivatives of the formula IIwhere R¹ is C₂ -C₁₂ -alkyl which is substituted by C₁ -C₁₂-alkoxycarbonyl.

The novel azulene derivatives of the formula II are useful intermediatesfor preparing the azulenesquaric acid dyes of the formula I according tothe invention.

They are obtained for example from substituted methylazulenes, forexample 4,6,8-trimethylazulene or guaiazulene, by anionization, forexample with lithium diisopropylamide, and subsequent alkylation withhalogen compounds of the formula IV

    R.sup.1 -Hal                                               (IV),

where R¹ is as defined above and Hal is halogen, in particular chlorine,bromine or iodine.

It is also possible, starting from the corresponding azulenecarboxylicacids, to obtain further products according to the invention. Forinstance, those azulene derivatives of the formulae IIa and IIb##STR10## where R¹ is in each case C₂ -C₁₂ -alkyl which is substitued bycarboxyl are particularly suitable for further derivatization. They canbe derivatized for example in a conventional manner to obtain therespective esters, nitriles or hydroxy compounds. A method of preparingazulenecarboxylic acids is described for example in Helv. Chim. Acta. 65(1982), 280-85.

Starting from the hydroxy compounds it is then possible to obtain, againin a conventional manner, those compounds of the formula II where R¹ isC₁ -C₁₂ -alkyl which is substituted by alkoxy, alkanoyloxy or benzoyloxyor the radical ##STR11## where R⁶ and R⁷ are each as defined above.

This takes the form for example of reacting a hydroxy compound of theformula VI ##STR12## where R², R³, R⁴ and R⁵ are each as defined aboveand L is C₁ -C₁₂ -alkylene, with alkylating agents (for example dimethylsulfate), carbonyl chlorides or phosphinoyl chlorides in the presence ofa base (for example triethylamine).

The compound of the formula V ##STR13## which is prepared fromguaiazulene and squaric acid, is known and described for example inAngew. Chem. 78 (1966) 937. The use thereof in optical storage media islikewise known, for example from DE-A-3,320,674 and the earlierapplication DE-A-3,703,985.

It is true that compound V shows good optical data, so that thin dyelayers produced therefrom are suitable for optical information recordingwithout a reflector layer, but to prepare spincoating formulations it isonly sufficiently soluble in halogenated hydrocarbons. In order thatstorage layers may be spincoated onto grooved polycarbonate substrates,a protective layer is therefore required against these aggressivesolvents. In addition, compound V tends to recrystallize in thin layers,so that the formulation must frequently be given a binder content of upto 30 percent in order to suppress recrystallization.

It is a further object of the present invention to provide a new opticalrecording medium containing azulenesquaric acid derivatives as storagematerials which is simply manufacturable, which is readily writable andsubsequently readily readable as well, to which end the signal-to-noiseratio should be as high as possible, and in which the storage layers areof high stability.

We have found that this object is achieved with an optical recordingmedium containing a base material and a radiation-sensitive thin coatingfilm which contains a dye with or without a binder, the dye having theformula I ##STR14## where R¹ is C₁ -C₁₂ -alkyl, which may be substitutedby halogen, amino, hydroxy C₁ -C₁₂ -alkoxy, phenyl, substituted phenyl,carboxyl, C₁ -C₁₂ -alkoxycarbonyl, C₁ -C₁₂ -haloalkoxycarbonyl, C₁ -C₁₂-phenylalkoxycarbonyl, cyano, C₁ -C₁₂ -alkanoyloxy, benzoyloxy,substituted benzoyloxy and/or by the radical ##STR15## where R⁶ and R⁷are identical or different and each is C₁ -C₄ -alkyl or phenylindependently of the other, carboxyl, C₁ -C₁₂ -alkoxycarbonyl, where thealkyl chain may be interrupted by one or more oxygen atoms, carbamoyl orC₁ -C₄ -monoalkyl- or -dialkylcarbamoyl and

R², R³, R⁴ and R⁵ are identical or different and each is hydrogen or C₁-C₁₂ -alkyl, which may be substituted by halogen, amino, C₁ -C₁₂-alkoxy, phenyl, substituted phenyl, carboxyl, C₁ -C₁₂ -alkoxycarbonylor cyano, independently of the others,

with the proviso that, when R⁵ is hydrogen, the positions ofsubstituents CH₂ -R¹ and R⁴ on either or both azulene rings may also beinterchanged for one another within an azulene ring and that R¹ is alsohydrogen when R⁵ is methyl or ethyl which may each be substituted byphenyl or substituted phenyl, or is C₃ -C₁₂ -alkyl or when at least oneof the two radicals R² and R⁴ is phenyl or substituted phenyl.

Preference is given to an optical recording medium which containsazulenesquaric acid dyes of the formula I where R², R³, R⁴ and R⁵ areeach C₁ -C₆ -alkyl and R¹ is as defined above.

Particular preference is given to an optical recording medium whichcontains azulenesquaric acid dyes of the formula I where R² and R⁴ areeach methyl, R³ and R⁵ are each hydrogen and R¹ is as defined above.

Very particular preference is given to an optical recording medium whichcontains azulenesquaric acid dyes of the formula I where R² and R⁴ areeach hydrogen, R³ is isopropyl, R⁵ is methyl and R¹ is as defined above.

Suitable base materials are conveniently transparent base materials,such as glass or plastics. Suitable plastics are for examplepoly(meth)acrylates, polycarbonates, polyesters, epoxies, polyolefins(for example polymethylpentene), polyamide, polyvinyl chloride,polystyrene or polyvinyl esters.

A preferred recording medium has a base material made of polycarbonateor poly(meth)acrylates, but in particular polycarbonate.

Preference is further given to an optical recording medium whichcontains from 1 to 30% by weight, based on the dye, of a binder.

The novel azulenesquaric acid dyes of the formula I, in particular thosewhere R¹ is C₁ -C₁₂ -alkyl which is substituted by C₁ -C₁₂-alkoxycarbonyl, show the same good optical properties as the knownbasic structure V. Furthermore, with the novel compounds the pure dyelayers are more stable. This is because to date the pure dye layer hasnot been found to recrystallize and thus does not need the addition of apolymeric binder. Moreover, the light fastness (stability) is alsodistinctly higher than that of existing methine dyes, so that theaddition of stabilizers to the layer formulation can be kept to aminimum. Of particular advantage is also the good solubility of thenovel dyes I in most organic solvents, so that these dyes can bespincoated directly (without protective layer) onto structured plasticssubstrates, in particular polycarbonate substrates.

As stated above, the spincoating solution preferably contains a binderin order to confer good longterm stability on the recording medium andin particular to optimize the viscosity of the spincoating solution.Preferably this solution contains from 1 to 30% by weight, based on thesolids content of the spincoating solution, of a binder. Suitablebinders are for example polyorganosiloxanes, epoxies,poly(meth)acrylates, polystyrene homopolymers and copolymers,polyvinylcarbazole, polyvinylpyrrolidone, polyimidazole copolymers,polyvinyl ester copolymers, polyvinyl ether copolymers, polyvinylidenechloride copolymers, acrylonitrile copolymers, polyvinyl chloride orcopolymers thereof, cellulose acetate or nitrocellulose.

A preferred recording medium has a binder based on avinylpyrrolidone/vinylacetate copolymer or a polyvinylchloride/polyvinyl ether copolymer.

The optical recording medium according to the invention isadvantageously produced by applying a solution containing organicbinder, azulenesquaric acid dye I and, if it is to be used, a binder byspincoating. Advantageously, the spincoating solution has a solidscontent of from 1 to 30% by weight, based on the solution.

Suitable solvents are for example propanol, isopropanol, butanol,diacetone alcohol, methyl ethyl ketone, toluene, bromoform,1,1,2-trichloroethane and mixtures thereof.

If desired, the solution may additionally contain up to 10% by weight,based on the solids content of the spincoating solution, of additives,for example antioxidants, singlet oxygen quenchers or UV-absorbers.

Preferably, the spincoating solution contains up to 5% by weight, basedon the solids content of the spincoating solution, of a mixture of aplurality of antioxidants, singlet oxygen quenchers and UV-absorbers. Onemploying antioxidants which likewise absorb in the near infrared, forexample nickel dithiolene complexes, as described for example inDE-A-3,505,750, DE-A-3,505,751 or S. H. Kim, M. Matsuoka, M. Yomoto, Y.Tsuchiya and T. Kitao, Dyes and Pigments, 8 (1987), 381-388, preferablyup to 10% by weight, based on the solids content of the spincoatingsolution, may be present in the solution.

For the purposes of the present invention, spincoating comprisesapplying the solution to the rotating base, which conveniently has around shape. However, it is also possible to apply the solution to theinitially stationary base and then to set the base material in rotation.The application of the solution to the base is conveniently effectedwith a syringe or capillary or by means of a mechanical pump.

The base generally rotates at a speed of 50 to 7,000 revolutions perminute (rpm), preferably from 500 to 5,000 rpm, the solutionadvantageously being applied at a relatively low speed (from about 500to 2,000 rpm) and thereafter spun dry at a higher speed (from about5,000 to 7,000 rpm). The thickness of the laser light sensitive layer isfrom 40 to 160 nm, preferably from 80 to 120 nm. It is dependent on thespeed of rotation, on the concentration and viscosity of the spincoatingsolution and on the temperature.

In the optical recording medium according to the invention, the laserlight sensitive layer is present in the form of a homogeneous, thin,smooth layer which is of high optical quality. For instance, thereflectivity values are in general within the range greater than 12%.

The novel recording medium, furthermore, is sufficiently sensitive atthe wavelength of a laser light source used that the incidence of lightpulses of an energy content of a few nJ which are focused to a focalpoint diameter of ≦1 μm leads to the formation of pits with an excellentsignal-to-noise ratio.

Laser light sources which are particularly highly suitable, on accountof the small size of the device, its low energy consumption and theoption of direct modulation of the optical power output by modulatingthe electrical drive current, are solid-state injection lasers whichemit in the near infrared, in particular the AlGaAs laser which operateswithin the wavelength region from about 750 to 900 nm.

The following Examples will illustrate the invention in more detail:

A) Preparation of azulene derivatives

EXAMPLE 1 Guaiazulenepropionic Acid(azulene-7-isopropyl-1-methyl-4-propionic acid) (IIb.9)

70.0 ml (0.12 mol) of a 15% strength by weight solution ofn-butyllithium in hexane are added dropwise at -40° C. under argon withstirring to a solution of 19.8 g (0.10 mol) of guaiazulene and 22.0 ml(0.16 mol) of diisopropylamine in 300 ml of anhydrous diethyl ether. Thesolution was then allowed to warm to 0° C. by stirring for 30 minutesand then cooled down again to -40° C., and a solution of 8.6 g (0.06mol) of bromoacetic acid in 50 ml of anhydrous ether was slowly addeddropwise. The blue reaction mixture was warmed to room temperature inthe course of 4 hours and subsequently stirred at room temperature forabout 12 hours. 100 ml of ice-water were then added for hydrolysis, andthe excess or unconverted guaiazulene was extracted with ether until theorganic phase was substantially colorless. A total of 7.5 g ofguaiazulene were recovered from the the combined organic phases. Theaqueous phase was covered with 300 ml of ether, and 2N hydrochloric acidwas added to liberate the guaiazulenepropionic acid. The organic phasewas separated off, washed with water until acid-free and dried oversodium sulfate. Removal of the solvent by evaporation left 12.3 g (80%based on bromoacetic acid) of guaiazulenepropionic acid in the form of ablue mass of crystals which can be used directly for esterification (seeExample 2). The direct conversion of guaiazulenepropionic acid withsquaric acid to dyes of the formula I (see Example 4) requiredsubsequent column chromatography over silica gel (9/1 methylenechloride/acetone) in order to remove traces of guaiazulene (about 0.3 g)and separate off a brown residue.

Yield: 10.5 g (68%); mp.: 139°-140° C.

IR (KBr): ν=3460 broad, 2961, 2925, 2864, 1699 (C=O)s, 1555, 1527, 1460,1419, 1408, 1389, 1301, 1215, 921, 776 cm⁻¹ ; ¹ H-NMR (CDCl₃): σ=1.38d(6H), 2.68 s(3H), 2.90 t(2H), 3.08 q(1H), 3.50 t(2H), 7.06 d(1H), 7.29d(1H), 7.43 d(d) (1H), 7.64 d(1H), 8.20 d(1H); ¹³ C-NMR (CDCl₃):σ=12.91, 24.72 (2C), 33.95, 35.27, 38.28, 112.06, 124.13, 125.58,133.53, 135.26, 136.42, 136.52, 136.77, 140.40, 146.01, 179.02; MS:m/e=256 (M⁶¹ , 100%), 241 (M⁶¹ -CH₃, 75%), 211, 195, 181, 165, 152, 141,128, 115.

The same method was used to prepare the 4-methyl-substitutedguaiazulene- and 4,6,8-trimethylazulenealkylcarboxylic acids of Table 1.

EXAMPLE 2 Methyl Guaiazulenepropionate (MethylAzulene-7-Isopropyl-1-Methyl-4-Propionate) (IIb.10)

12.8 g (0.05 mol) of guaiazulenepropionic acid (Example 1), 12 ml ofmethanol and 0.3 g of p-toluenesulfonic acid were refluxed in 250 ml ofcarbon tetrachloride. The reaction, which was monitored by means of thinlayer chromatography (TLC), came to an end after about 6 hours. Thereaction mixture was then discharged onto water, and the organic phasewas washed with saturated sodium bicarbonate solution and then withwater and subsequently dried over sodium sulfate. The highly viscouscrude product (13.1 g, 97%) was purified by column chromatography overneutral silica gel (9/1 methylene chloride/acetone).

Yield: 12.0 g (89%) of a blue highly viscous oil.

UV (CH₂ Cl₂): λmax=300 nm, ε=43130; IR (film): ν=2958, 2927, 1739(C=O)s, 1555, 1461, 1435, 1388, 1363, 1195, 1170, 780 cm⁻¹ ; ¹ H-NMR(CDCl₃): σ=1.35 d(6H), 2.65 s(3H), 2.84 t(2H), 3.18 q(1H), 3.47 t(2H),3.71 s(3H), 7.01 d(1H), 7.29 d(1H), 7.42 d(1H), 7.63 d(1H), 8.19 d(1H);d(1H), 7.29 d(1H), 7.43 d(d) (1H), 7.64 d(1H), 8.20 d(1H); ¹³ C-NMR(CDCl₃): σ=12.90 24.72 (2C), 33.31, 35.37, 38.27, 51.66, 112.14, 124.24,125.50, 133.44, 135.24, 136.40, 136.74 (2C), 140.28, 146.47, 173.40; MS:m/e=270 (M.sup.⊕, 100%).

EXAMPLE 3 Isopropyl Guaiazulenepropionate (IsopropylAzulene-7-Isopropyl-1-Methyl-4-Propionate) (IIb.13)

The preparation was carried out similarly to Example 2 using 6.4 g (25mmol) of guaiazulenecarboxylic acid, except that methanol was replacedby isopropanol. The reaction came to an end after 10 hours.

Yield 5.3 g (71%) of a blue oil.

IR (film): ν=2959, 2932, 1730 (C=O)s, 1556, 1464, 1387, 1372, 1260,1181, 1146, 1108 s, 982 cm⁻¹ ; ¹ H-NMR (CDCl₃): S=1.24 d(8H), 1.38d(6H), 2.70 s(3H), 2.83 t(2H), 3.12 q(1H), 3.51 t(2H), 5.07 q(1H), 7.3d(d) (2H), 7.35 s(1H), 7.72 s(1H), 8.26 s(1H).

¹³ C-NMR (CDCl₃): S=12.86, 21.82 (2C), 24.71 (2C), 33.38, 35.99, 38.27,67.76, 112.24, 124.30, 125.43, 133.29, 135.12, 136.49, 136.72, 136.89,140.17, 146.69, 172.41. MS: m/e=298 (M.sup.⊕, 100%).

The method of Examples 2 and 3 was used to prepare the4-methyl-substituted guaiazulene- and4,6,8-trimethylazulene-alkylcarboxylic esters of Table 1.

EXAMPLE 4 Guaiazulenepropanol(7-Isopropyl-1-Methyl-4-(3-Hydroxypropyl)azulene) (IIb.45)

10 g (37 mmol) of methyl guaiazulenepropionate (Example 2) were reducedwith 1.5 g (39 mmol) of lithium aluminum hydride in 200 ml of anhydrousether. After the reaction had ended (TLC check), the reaction mixturewas admixed with a little methanol and worked up with water, and thecrude product was filtered through a short silica gel column.

Yield: 8.5 g (95%).

MS: m/e=242 (M.sup.⊕, 20%), 198 (n-C₂ H₄ O, 100%), 183 (40%), 43.

EXAMPLE 5 4,6-Dimethyl-8-(3-hydroxypropyl)azulene (IIa.16)

5.0 g (20.7 mmol) of 4,6-dimethyl-8-2-(ethoxycarbonyl)ethyl)azulene(IIa.10) were reduced with 0.8 g (21 mmol) of lithium aluminum hydridein 100 ml of anhydrous tetrahydrofuran. After the reaction had ended(TLC check) the reaction mixture was admixed with a little methanol andworked up with water, and the crude product (4.1 g) was chromatographedover silica gel.

Yield: 2.5 g (56%).

¹ H-NMR (CDCl₃): S=1.65 s broad (1H, OH), 2.10 q(2H), 2.63 s(3H), 2.86s(3H), 3.29 t(2H), 3.72 t(2H), 7.02 s(1H), 7.02 s(1H), 7.06 s(1H), 7.36m(1H), 7.64 s(1H).

MS: m/e=214 (M.sup.⊕, 25%), 170 (M-C₂ H₄ O, 100%), 155 (M.sup.⊕ -C₃ H₆OH, 60%), 141, 128, 115, 43 (25%).

EXAMPLE 6 3-(7-Isopropyl-1-methyl)azulen-4-yl-2-ethylpropionic acid

70.0 ml (0.12 mol) of a 15% strength by weight solution ofn-butyllithium in hexane were added dropwise at -10° C. with stirringunder argon to a solution of 19.8 g (0.10 mol) of guaiazulene and 22.0ml (0.16 mol) of diisopropylamine in 300 ml of anhydrous methyltert-butyl ether. The temperature of the solution was allowed to rise to0° C. in the course of 30 minutes while stirring, and then the solutionwas cooled down again to -5° C., and a solution of 12.4 g (0.07 mol) ofDL-2-bromobutyric acid in 50 ml of anhydrous methyl tert-butyl ether wasthen slowly added dropwise. The blue reaction mixture was warmed to roomtemperature in the course of 4 hours and subsequently stirred at roomtemperature for about 18 hours. 100 ml of ice-water were then added forhydrolysis, and excess or unconverted guaiazulene was then extractedwith ether until the organic phase was substantially colorless. Theaqueous phase was covered with 300 ml of methyl tert-butyl ether, and 2Nhydrochloric acid was added to free the3-(7-isopropyl-1-methyl)azulen-4-yl-2-ethylpropionic acid. The organicphase was separated off, washed with water until acid-free and driedover sodium sulfate. Removal of the solvent by evaporation left 13.1 g(60% based on DL-2-bromobutyric acid) of3-(azulene-7-isopropyl-1-methyl-4)-2-ethylpropionic acid in the form ofa blue oil which can be used directly for esterification (see Example2). Direct conversion of3-(azulene-7-isopropyl-1-methyl-4)-2-ethylpropionic acid with squaricacid to dyes of the formula I required subsequent column chromatographyover silica gel (9/1 methylene chloride/acetone) in order to removetraces of guaiazulene (about 0.3 g) and separate the product fromDL-2-bromobutyric acid. Physical data:

IR (KBr): ν=3064 (OH); 2962, 2934, 2876 (CH), 1706 s(C=O); 1555, 1461,1422, 1387, 1285 cm⁻¹ ;

¹ H-NMR (CDCl₃): δ=0.98 t(3H), 1.34 d(6H), 1.70 ddq(2H), 2.65 s(3H),3.00 m(1H), 3.05 q(1H), 3.25 ABM(1H), 3.55 ABM(1H), 6.98, 7.35 AB(2H; 7,8H), 7.28, 7.59 AB (2H; 4, 5H), 8.19 s(1H), 11.45 s broad (1H; CO₂ H)→¹³C-NMR (CDCl₃): δ=11.66, 12.84, 24.68 (2C), 25.40, 38.29, 39.98, 48.51,112.63, 124.74, 125.50, 133.28, 134.77, 136.79, 136.87, 137.63, 140.28,145.16, 181.83;

MS: m/e=284 (M⁶¹, 90%), 269, 198 (100%).

EXAMPLE 7 N-Butyl 3-(7-Isopropyl-1-Methyl)Azulen-4-yl-2-Ethylpropionate

10.0 g (0.035 mol) of3-(7-isopropyl-1-methyl)azulen-4-yl-2-ethylpropionic acid (Example 6),20 ml of n-butanol and 0.3 g of p-toluenesulfonic acid were refluxed in100 ml of carbon tetrachloride. After the reaction had ended (monitoringby thin layer chromatography; about 6 hours), the reaction mixture wasdischarged onto water, and the organic phase was washed with saturatedsodium bicarbonate solution and then with water and subsequently driedover sodium sulfate. The highly viscous crude product (8.6 g, 72%) waspurified by column chromatography over silica gel (methylene chloride).

Physical data:

IR (KBr): ν=2981s (CH), 2871s, 1731s (C=O); 1460s, 1365, 1219, 1185,1069s (C-O), 1031, 910s cm⁻¹ ;

¹ H-NMR (CDCl₃): δ=0.85 t(3H), 0.95 t(3H), 1.24 ps.q(2H), 1.38 d(6H),1.45 ps.q(2H), 1.72 dq(2H), 2.65 s(3H), 2.90 ps.t(1H), 3.06 q(1H), 3.28,3.45 ABM(2H), 3.98 t(2H), 6.96, 7.38 AB(2H; 7, 8H), 7.26, 7.60 AB(2H;4,5H), 8.18 s(1H);

¹³ C-NMR (CDCl₃): δ=11.79, 12.84, 13.58, 19.17, 24.72 (2C), 25.90,30.84, 38.34, 40.49, 48.96, 64.15, 112.65, 124.86, 125.42, 133.21,134.77, 136.74, 137.76, 140.17, 145.77, 175.58, 179.05;

MS: m/e=340 (M.sup.⊕, 100%), 325, 312, 297, 283, 267, 257, 239, 223,209, 198 (95%), 183, 167, 155.

EXAMPLE 8 3-(7-Isopropyl-1-Methyl)Azulen-4-yl-2-Ethylpropanol

A solution of 14.2 g (0.05 mol) of3-(7-isopropyl-1-methyl)azulen-4-yl-2-ethylpropionic acid in 100 ml oftetrahydrofuran was admixed with 2.8 g of lithium alanate a little at atime, and the reaction mixture was stirred at room temperature for 2hours. It was then hydrolysed with a total of 150 ml of water andrepeatedly extracted with methylene chloride. The crude productremaining on drying the organic phase over sodium sulfate and removingthe solvent under reduced pressure was purified by column chromatography(silica gel; methylene chloride, methanol) leaving 8.3 g (66%) of3-(7-isopropyl-1-methyl)azulen-4-yl-2-ethylpropanol as a deep blue oil.

Physical data:

IR (KBr): ν=3350 broad (OH); 2958, 2927, 2872 (CH); 1553, 1461, 1421,1387 cm⁻¹ ;

¹ H-NMR (CDCl₃): δ=0.98 t(3H), 1.35 d(6H), 1.49 dq(2H), 2.00 m(1H), 2.66s(3H), 3.05 q(1H), 3.08, 3.18 ABM(2H), 3.50 mc(2H), 6.98, 7.36 AB(2H; 7,8H), 7.32, 7.62 AB (2H; 4, 5H), 8.19 s(1H);

¹³ C-NMR (CDCl₃): δ=11.46, 12.90, 24.39, 24.73 (2C), 38.23, 39.65,44.34, 64.71, 112.58, 125.25 (2C), 133.17, 134.82, 136.10, 136.45,137.98, 139.80, 147.86;

MS: m/e=270 (M.sup.⊕, 50%), 198 (100%).

EXAMPLE 9 3-(7-Isopropyl-1-methyl)azulen-4-yl-propanol

A solution of 13.5 g (0.05 mol) of3-(7-isopropyl-1-methyl)azulen-4-yl-propionic acid was reacted with 3.0g of lithium alanate in 100 ml of tetrahydrofuran and worked up, bothsteps being carried out as described in Example 8. Column chromatography(silica gel; methylene chloride, methanol) left 6.5 g (52%, of3-(7-isopropyl-1-methyl)azulen-4-yl-propanol as a blue oil.

EXAMPLE 10 3-(7-Isopropyl-1-methyl)azulen-4-yl-n-propanyl pivalate

9.6 g (0.08 mol) of pivaloyl chloride in 20 ml of tetrahydrofuran wereslowly added dropwise at room temperature to a solution of 9.6 g (0.04mol) of azulene-7-isopropyl-1-methyl-4-propanol and 40 ml oftriethylamine in 200 ml of tetrahydrofuran. The reaction mixture wassubsequently stirred for 6 hours and then discharged onto 200 ml ofwater, and the mixture was repeatedly extracted with methylene chloride.Drying the organic phase with sodium sulfate and drawing off the solventleft 12.1 g (93%) of 3-(7-isopropyl-1-methyl)azulen-4-yl-n-propanylpivalate as a dark blue oil which is used without purification for thedyeing reaction (similarly to Example 8).

EXAMPLE 11 3-(7-Isopropyl-1-methyl)azulen-4-yl-n-propanylbiphenylphosphinate

15.6 g (0.066 mol) of biphenylphosphinoyl chloride in 20 ml oftetrahydrofuran were slowly added dropwise at room temperature to asolution of 8.0 g (0.03 mol) of azulene-7-isopropyl-1-methyl-4-propanoland 20 ml of triethylamine in 100 ml of tetrahydrofuran. The batch wassubsequently stirred for 6 hours and worked up as described in Example10. Filtration of the crude product through silica gel (methylenechloride) left 12.2 g (83%) of3-(7-isopropyl-1-methyl)azulen-4-yl-n-propanylbiphenyl phosphinate as adeep blue oil. Physical data:

IR (KBr): ν=3060, 2958 (CH); 1439 s(PO); 1228s, 1130s, 1013s, 997s, 729,697, 560, 536 cm⁻¹ ;

¹ H-NMR (CDCl₃): δ=1.37 d(6H), 2.28 mc(2H), 2.68 s(3H), 3.08 q(1H), 3.31ps.t(2H), 4.15 ps.q(2H), 7.00, 7.50 AB(2H: H-7.8), 7.28, 7.63 AB(2H;4.5-H), 7.45 m(6H; P-PhH), 7.85 m(4H; Ph-H), 8.20 s(1H); ³¹ p-NMR(CDCl₃): δ=32.10 ppm;

MS: m/e=442 (M.sup.⊕, 30%), 224, 209, 198, 183, 181.

EXAMPLE 12 1-(p-Methoxybenzyl)-4,6,8-trimethylazulene

To 3.0 g (0.04 mol) of trimethylazulene in 40 ml of absolute diethylether were added 4.0 g of 85% strength by weight of ethereal HBF₄solution, and the mixture was stirred until colorless. The precipitateformed was filtered off with suction, washed with ether and then heatedtogether with 28 g of p-methoxybenzaldehyde to from 90° to 100° C. 100ml of ether were added, and the resulting red precipitate was filteredoff with suction and washed with diethyl ether. The precipitate was thensuspended in 200 ml of diethyl ether and admixed, by stirring, with 3.5g of lithium alanate added a little at a time. After all the lithiumalanate had been added, the mixture was hydrolyzed with water and 2Nsulfuric acid. The organic phase was separated off and dried over sodiumsulfate. The crystalline residue left on drawing off the solvent waspurified by filtration through silica gel (methylene chloride). 1.5 g(13%, based on trimethylazulene) of1-(p-methoxybenzyl)-4,6,8-trimethylazulene were obtained as bluecrystals.

The same method was used to obtain the azulene derivatives of theformula ##STR16## listed in Table 1.

                                      TABLE 1                                     __________________________________________________________________________    Compound No.                                                                          R.sup.1       R.sup.2  R.sup.3                                                                             R.sup.4  R.sup.5                         __________________________________________________________________________    II.1    CH.sub.2 CO.sub.2 sC.sub.4 H.sub.9                                                          H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.2                                                                                   ##STR17##    H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.3    CH.sub.2 CO.sub.2 CH.sub.2 CH.sub.2 Br                                                      H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.4                                                                                   ##STR18##    H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.5                                                                                   ##STR19##    H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.6                                                                                   ##STR20##    H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.7                                                                                   ##STR21##    H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.8                                                                                   ##STR22##    H        CH(CH.sub.3 ).sub.2                                                                 H        CH.sub.3                        II.9                                                                                   ##STR23##    H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.10                                                                                  ##STR24##    H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.11                                                                                  ##STR25##    H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3 see Ex. 7              II.12                                                                                  ##STR26##    H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.13   CH.sub.2 OC(O)CH.sub.3                                                                      H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.14   (CH.sub.2).sub.2 OC(O)CH.sub.3                                                              H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.15   (CH.sub.2).sub.2 OC(O)C(CH.sub.3).sub.3                                                     H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3 see Ex. 10             II.16   (CH.sub.2).sub.2 OC(O)C.sub.9 H.sub.19                                                      H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.17                                                                                  ##STR27##    H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.18                                                                                  ##STR28##    H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.19                                                                                  ##STR29##    H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.20                                                                                  ##STR30##    H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3 see Ex. 11             II.21                                                                                  ##STR31##    H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.22                                                                                  ##STR32##    H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.23                                                                                  ##STR33##    H        CH(CH.sub.3).sub.2                                                                  H        CH.sub.3                        II.24   (CH.sub.2).sub.2 OCH.sub.3                                                                  H        CH.sub.3                                                                            H        CH.sub.3                        II.25   CO.sub.2 C.sub.2 H.sub.5                                                                    CH.sub.3 H     CH.sub.3 H                               II.26   CO.sub.2 nC.sub.3 H.sub.7                                                                   CH.sub.3 H     CH.sub.3 H                               II.27   CO.sub.2 iC.sub.3 H.sub. 7                                                                  CH.sub.3 H     CH.sub.3 H                               II.28   H             CH.sub.3 H     CH.sub.3 CH(CH.sub.3).sub.2              II.29   H             CH.sub.3 H     CH.sub.3                                                                                ##STR34##                      II.30   H             CH.sub.3 H     CH.sub.3                                                                                ##STR35##                      II.31   H             CH.sub.3 H     CH.sub.3                                                                                ##STR36##                      II.32   H             CH.sub.3 H     CH.sub.3                                                                                ##STR37##                      II.33   H             CH.sub.3 H     CH.sub.3                                                                                ##STR38##                      II.34   H             CH.sub.3 H     CH.sub.3                                                                                ##STR39##                      II.35   H             CH.sub.3 H     CH.sub.3                                                                                ##STR40##                      II.36   H             CH.sub.3 H     CH.sub.3                                                                                ##STR41##                      II.37   H             CH.sub.3 H     CH.sub.3                                                                                ##STR42##                      II.38   H             CH.sub.3 H     CH.sub.3                                                                                ##STR43##                      II.39   H             CH.sub.3 H     CH.sub.3                                                                                ##STR44##                      II.40   H                                                                                            ##STR45##                                                                             H     CH.sub.3 H                               II.41   H                                                                                            ##STR46##                                                                             H                                                                                    ##STR47##                                                                             H                               __________________________________________________________________________

                                      TABLE 2                                     __________________________________________________________________________    List of azulene derivatives of the abovementioned                             formulae IIa and IIb used an characterization of the                          novel compounds                                                                                   Comments: Literature references.sup.1) and                Compound            characterization of novel                                 No.   R.sup.1       compounds                                                 __________________________________________________________________________    IIa.1 H             Reference substance: 4,6,8-trimethyl-                                         azulene (mp.: 78-80° C.)                           IIa.2 CH.sub.3      C.sub.14 H.sub.16 (184,28); MS: m/e = 184                                     (M.sup.⊕,                                                                 100%), 169, 155, 154.                                     IIa.3 CH(CH.sub.3).sub.2                                                                          C.sub.16 H.sub.20 (212,34); MS: m/e = 212                                     (M.sup.⊕),                                                                197, 43.                                                  IIa.4 C.sub.4 H.sub.9                                                                             C.sub.17 H.sub.22 (226,36); MS: m/e = 226                                     (M.sup.⊕,                                                                 100%), 211, 196, 154.                                     IIa.5 CH.sub.2 C.sub.6 H.sub.5                                                                    K. Hafner et al., Liebigs Ann. 650,                                           (1961), 80 (HW.sup.1), p. 338);                                               C.sub.20 H.sub.21 (261,39); MS: m/e = 261                                     (M.sup.⊕,                                                                 20%), 246 (M.sup.⊕ -CH.sub.3), 184 (M.sup.⊕                           -C.sub.6 H.sub.5),                                                            170 (M.sup.⊕ -CH.sub.2 C.sub.6 H.sub.5), 91                               (C.sub.7 H.sub.7, 100%).                                  IIa.6 CO.sub.2 H    K. Hafner et al., Liebigs Ann. 650,                                           (1961), 80                                                                    (HW.sup.1), p. 341); mp.: 121-122° C.                                  C.sub.15 H.sub.14 O.sub.2 (226.28); MS: m/e = 226                             (M.sup.⊕,                                                                 100%); IR: - ν = 1698 (C═O) cm.sup.-1.             IIa.7 CO.sub.2 CH.sub.3                                                                           K. Hafner et al., Liebigs Ann. 650,                                           (1961), 80                                                                    (HW.sup.1), p. 341); mp.: 43-44° C.                                    C.sub.16 H.sub.16 O.sub.2 (240,30); MS: m/e = 240                             (M.sup.⊕,                                                                 100%), 225, 210, 194, 166, 59;                                                IR: - ν = 1732 (C═O) cm.sup.-1.                    IIa.8 CO.sub.2 C.sub.4 H.sub.9                                                                    C.sub.19 H.sub.25 O.sub.2 (285,41); MS: m/e = 285                             (M.sup.⊕), 270, 228, 212, 184, 101, 73;                                   IR: - ν = 1731 (C═O) cm.sup.- 1.                   IIa.9 CH.sub.2 CO.sub.2 H                                                                         R. Neidlein and W. Kramer, Helv.                                              Chim. Acta 65, (1982), 280                                                    mp.: 90-92° C.                                     IIa.10                                                                              CH.sub.2 CO.sub.2 CH.sub.3                                                                  violet oil: IR (Film): ν = 3090,                                           3063, 2985, 2945, 1737 (C═O)s, 1576,                                      1543, 1488, 1435, 1322, 1211, 1196,                                           1170 (C--O), 848, 735 cm.sup.-1 ; .sup.1 H-NMR                                (CDCl.sub.3): S = 2.59 s(3H), 2.81 t(2H),                                     2.82 s(3H), 3.50 t(3H), 3.66 s(3H),                                           7.01 s(1H), 7.04 s(1H), 7.37 d(1H),                                           7.42 d(1H), 7.68 t(1H); .sup.13 C-NMR                                         (CDCl.sub.3): δ = 25.10, 28.67, 34.23,                                  35.82, 51.66, 115.37, 116.37, 126.20,                                         127.38, 132.94, 135.47, 136.20,                                               145.63, 146.56, 147.75, 173.26;                                               MS: m/e = 242 (M.sup.⊕, 100%),                                            227 (M.sup.⊕ -CH.sub.3, 8%) 211 (M.sup.⊕                              -OCH.sub.3, 15%)                                                              183 (M.sup.⊕ -CO.sub.2 CH.sub.3, 50%)                                     168, 153, 141, 43 (CH.sub.3 CO.sup.⊕, 40%).           IIa.11                                                                              CH.sub. 2 CO.sub.2 C.sub.2 H.sub.5                                                          C.sub.17 H.sub.20 O.sub.2 (256, 35); MS: m/e = 256                            (M.sup.⊕,                                                                 100%); IR: - ν = 2968, 1733 s(C═O),                                    1576, 1544, 1436, 1371, 1276, 1179,                                           1158, 1034, 752 cm.sup.-1.                                                    .sup.1 H-NMR (CDCl.sub.3): δ = 1.24 t(3H),                              2.61                                                                          s(3H), 2.82 q(2H), 2.86 s(3H), 3.50                                           t(2H), 4.15 q(2H), 7,04 s(1H), 7.06                                           s(1H), 7.34 d(1H), 7.39 d(1H), 7.65                                           t(1H);                                                                        .sup.13 C-NNR (CDCl.sub.3): δ = 14.26, 25.03,                           28.64, 34.32, 36.21, 60.49, 115.62,                                           116.53, 126.20, 127.35, 133.06,                                               135.84, 136.55, 145.57, 146.41,                                               147.96, 172.81.                                           IIa.12                                                                              CH.sub.2 CO.sub.2 nC.sub.3 H.sub.7                                                          C.sub.18 H.sub.22 O.sub.2 (270,37); MS: m/e = 270                             (M.sup.⊕);                                                                IR: - ν = 2967, 1733 s(C═O), 1576,                                     1544, 1463, 1436, 1276, 1211, 1177,                                           752 cm.sup.-1.                                                                .sup.1 H-NMR (CDCl.sub. 3): δ = 0.93 t(3H),                             1.66                                                                          q(2H), 2.60 s(3H), 2.85 q(2H), 2.86                                           s(3H), 3.52 t(2H), 4.08 q(2H), 7.04                                           s(1H), 7.07 s(1H), 7.35 d(1H), 7.40                                           d(1H), 7.67 t(1H);                                                            .sup.13 C-NMR (CDCl.sub.3): δ = 10.34, 22.09,                           25.04, 28.64, 34.33, 36.17, 66.21,                                            115.57, 116.49, 126.18, 127.35,                                               133.03, 135.78, 136.50, 145.58,                                               146.43, 147.95, 172.90.                                   IIa.13                                                                              CH.sub.2 CO.sub.2 iC.sub.3 H.sub.7                                                          C.sub.18 H.sub.22 O.sub.2 (270,37);                                           MS: m/e = 270 (M.sup.⊕, 100%);                                            IR: - ν = 1732 (C═O) cm.sup.-1.                                        .sup.1 H-NMR (CDCl.sub.3): δ = 1.21 d(6H),                              2.59                                                                          s(3H), 2.80 t(2H), 2.83 s(3H), 3.49                                           t(2H), 5.04 q(1H), 7.03 s(1H), 7.06                                           s(1H), 7.34 d(1H), 7.40 d(1H), 7.64                                           t(1H);                                                                        .sup.13 C-NMR (CDCl.sub.3): δ = 21.86 (2C),                             25.02, 28.63, 34.31, 36.49, 67.86,                                            115.61, 116.47, 126.19, 127.31,                                               133.00, 135.82, 136.51, 145.55,                                               146.37, 148.03, 172.36.                                   IIa.14                                                                              CH.sub.2 CO.sub.2 C.sub.4 H.sub.9                                                           C.sub.19 H.sub.24 O.sub.2 (284.40);                                           MS: m/e = 284 (M.sup.⊕, 100%);                                            IR: - ν = 1730 (C═O) cm.sup.-1.                    IIa.15                                                                              CH.sub.2 CO.sub.2 C.sub.8 H.sub.17                                                          C.sub.23 H.sub.32 O.sub.2 (340.51); MS: m/e = 340                             (M.sup.⊕);                                                                IR: - ν = 1730 (C═O) cm.sup.-1.                    IIa.16                                                                              (CH.sub.2).sub.2 OH                                                                         see Example 5                                             IIa.17                                                                              (CH.sub.2).sub.2 CO.sub.2 H                                                                 C.sub.16 H.sub.18 O.sub.2 (242,34); MS: m/e = 242                             (M.sup.⊕,                                                                 100%); IR: - ν = 2957, 2924, 1695                                          (C═O)s, 1466, 1434, 1416, 1287, 1274,                                     1207, 784 cm.sup.-1 ;                                                         .sup.1 H-NMR (CDCl.sub.3): δ = 2.16 h(2H),                              2.42                                                                          t(2H), 2.57 s(3H), 2.82 s(3H), 3.20                                           t(2H), 6.99 s(2H), 7.34 d(1H), 7.39                                           d(1H), 7.64 t(1H);                                                            .sup.13 C-NMR (CDCl.sub.3): δ = 24.99, 26.48,                           28.62, 33.88, 38.10, 115.75, 116.43,                                          126.28, 127.11, 132.82, 136.17,                                               136.38, 145.45, 146.23, 148.80,                                               179.44.                                                   IIa.18                                                                              (CH.sub.2).sub.2 CO.sub.2 CH.sub.3                                                          C.sub.17 H.sub.20 O.sub.2 (256,35); MS: m/e = 256                             (M.sup.⊕,                                                                 100%); IR: - ν = 1729 (C═O) cm.sup.-1.             IIa.19                                                                              (CH.sub.2).sub.2 CO.sub.2 C.sub.2 H.sub.5                                                   C.sub.18 H.sub.22 O.sub.2 (270,37); MS: m/e = 270                             (M.sup.⊕,                                                                 100%); IR: - ν = 1730 (C═O) cm.sup.-1.             IIa.20                                                                              (CH.sub.2).sub.2 CO.sub.2 iC.sub.3 H.sub.5                                                  C.sub.19 H.sub.24 O.sub.2 (284,40); MS: m/e = 284                             (M.sup.⊕,                                                                 100%); IR: - ν = 1733 (C═O) cm.sup.-1.             IIa.21                                                                              (CH.sub.2).sub.2 CO.sub.2 C.sub.4 H.sub.9                                                   C.sub.20 H.sub.26 O.sub.2 (298,43); MS: m/e = 298                             (M.sup.⊕,                                                                 100%); IR: - ν = 1731 (C═O) cm.sup.-1.             IIa.22                                                                              (CH.sub.2).sub.3 OH                                                                         C.sub.16 H.sub.20 O.sub.2 (228,34); MS: m/e = 228                             (M.sup.⊕), 211; IR: - ν = 3520 (OH)                                    cm.sup.-1.                                                IIa.23                                                                              (CH.sub.2).sub.4 CO.sub.2 H                                                                 C.sub.18 H.sub.22 O.sub.2 (270,37); MS: m/e = 270                             (M.sup.⊕);                                                                IR: - ν = 2959, 2926, 1697 (C═O)s cm.sup.-1.       IIa.24                                                                              (CH.sub.2).sub.4 CO.sub.2 CH.sub.3                                                          C.sub.18 H.sub.24 O.sub.2 (284,40); MS: m/e = 284                             (M.sup.⊕);                                                                IR: - ν = 1732 (C═O) cm.sup.-1.                    IIa.25                                                                              (CH.sub.2).sub.5 CO.sub.2 H                                                                 C.sub.19 H.sub.24 O.sub.2 (284,40); MS: m/e = 284                             (M.sup.⊕);                                                                IR: - ν = 2957, 2925, 1696 (C═O)s cm.sup.-1.       IIa.26                                                                              (CH.sub.2).sub.5 CO.sub.2 CH.sub.3                                                          C.sub.20 H.sub.26 O.sub.2 (298,43); MS: m/e = 298                             (M.sup.⊕);                                                                IR: - ν = 1730 (C═O) cm.sup.-1.                    IIa.27                                                                              (CH.sub.2).sub.9 CO.sub.2 H                                                                 C.sub.23 H.sub.32 O.sub.2 (340,51); MS: m/e = 340                             (M.sup.⊕);                                                                IR: - ν = 2958, 2927, 1697 (C═O)s cm.sup.-1.       IIa.28                                                                              (CH.sub.2).sub.9 CO.sub.2 CH.sub.3                                                          C.sub.24 H.sub.34 O.sub.2 (354,54); MS: m/e = 354                             (M.sup.⊕);                                                                IR: - ν = 1733 (C═O) cm.sup.-1.                    IIb.29                                                                              H             Reference substance: guaiazulene                                              (mp.: 29-30° C.)                                   IIb.30                                                                              CH.sub.3      K. Hafner, H. Pelster and H. Patzelt,                                         Liebigs Ann. 650, (1961), 80; (HW.sup.1),                                     p. 336f);                                                                     C.sub.16 H.sub.20 (212,34); MS: m/e = 212                                     (M.sup.⊕,                                                                 100%).                                                    IIb.31                                                                              CH(CH.sub.3).sub.2                                                                          C.sub.18 H.sub.24 (240,39); MS: m/e = 240                                     (M.sup.⊕ ,                                                                100%).                                                    IIb.32                                                                              C.sub.4 H.sub.9                                                                             C.sub.19 H.sub.26 (254,42); MS: m/e = 254                                     (M.sup.⊕,                                                                 100%).                                                    IIb.33                                                                              CH.sub.2 C.sub.6 H.sub.5                                                                    C.sub.22 H.sub.24 (288,43); MS: m/e = 288                                     (M.sup.⊕),                                                                91 (C.sub.7 H.sub.7.sup.⊕, 100%),                     IIb.34                                                                              CO.sub.2 H    K. Hafner et al., Liebigs Ann. 650,                                           (1961), 80, (HW.sup.1), p. 341);                                              mp.: 102-103° C.;                                                      C.sub.16 H.sub.18 O.sub.2 (242,32); MS: m/e = 242                             (M.sup.⊕,                                                                 100%); IR: - ν = 1702 (C═O) cm.sup.-1.             IIb.35                                                                              CO.sub.2 CH.sub.3                                                                           C.sub.17 H.sub.20 O.sub.2 (256,35); MS: m/e = 256                             (M.sup.⊕,                                                                 100%); IR: - ν = 1731 (C═O) cm.sup.-1.             IIb.36                                                                              CO.sub.2 C.sub.4 H.sub.9                                                                    C.sub.20 H.sub.26 O.sub.2 (298,43); MS: m/e = 298                             (M.sup.⊕,                                                                 100%); IR: - ν  = 1731 (C═O) cm.sup.-1.            IIb.37                                                                              CH.sub.2 CO.sub.2 H                                                                         C.sub.17 H.sub.20 O.sub.2 (256,35); MS: m/e = 256                             (M.sup.⊕,                                                                 100%); IR: - ν = 1704 (C═O) cm.sup.-1.             IIb.38                                                                              CH.sub.2 CO.sub.2 CH.sub.3                                                                  C.sub.18 H.sub.22 O.sub.2 (270,37); MS: m/e = 270                             (M.sup.⊕,                                                                 100%); IR: - ν = 1735 (C═O) cm.sup.-1.             IIb.39                                                                              CH.sub.2 CO.sub.2 C.sub.2 H.sub.5                                                           C.sub.19 H.sub.24 O.sub.2 (284,40); MS: m/e = 284                             (M.sup.⊕,                                                                 100%); IR: - ν = 1732 (C═O) cm.sup.-1.             IIb.40                                                                              CH.sub.2 CO.sub.2 nC.sub.3 H.sub.7                                                          C.sub.20 H.sub.26 O.sub.2 (298,43); MS: m/e = 298                             (M.sup.⊕,                                                                 100%); IR: - ν = 1733 (C═O) cm.sup.-1.             IIb.41                                                                              CH.sub.2 CO.sub.2 iC.sub.3 H.sub.7                                                          C.sub.20 H.sub.26 O.sub.2 (398,43); MS: m/e = 298                             (M.sup.⊕,                                                                 100%); IR: - ν = 1730 (C═O) cm.sup.-1.             IIb.42                                                                              CH.sub.2 CO.sub.2 C.sub.4 H.sub.9                                                           C.sub.21 H.sub.28 O.sub.2 (312,45); MS: m/e = 312                             (M.sup.⊕,                                                                 100%); IR: - ν = 1731 (C═O) cm.sup.-1.             IIb.43                                                                              CH.sub.2 CO.sub.2 C.sub.8 H.sub.17                                                          C.sub.25 H.sub.36 O.sub.2 (368,56); MS: m/e = 368                             (M.sup.⊕,                                                                 100%); IR: - ν = 1730 (C═O) cm.sup.-1.             IIb.44                                                                              CH.sub.2 CO.sub.2 [(CH.sub.2).sub.2 O].sub.2 C.sub.2 H.sub.5                                C.sub.23 H.sub.34 O.sub.4 (374,52);                                           IR: - ν = 1731 (C═O) cm.sup.-1.                    IIb.45                                                                              (CH.sub.2).sub.2 OH                                                                         see Example 4                                             IIb.46                                                                              (CH.sub.2).sub.2 CO.sub.2 H                                                                 C.sub.18 H.sub.22 O.sub.2 (270,37); MS: m/e = 270                             (M.sup.⊕,                                                                 100%); IR: - ν = 1702 (C═O) cm.sup.-1.                                 .sup.1 H-NMR (CDCl.sub.3): δ = 1.36 d(6H),                              2.19                                                                          p(2H), 2.28 t(2H), 2.68 s(3H), 3.09                                           q(1H), 3.23 t(2H), 7.01 d(1H), 7.30                                           d(1H), 7.34 d(1H), 7.64 d(1H), 8.18                                           s(1H).                                                    IIb.47                                                                              (CH.sub.2).sub.2 CO.sub.2 CH.sub.3                                                          C.sub.19 H.sub.24 O.sub.2 (284,40); MS: m/e = 284                             (M.sup.⊕,                                                                 100%); IR: - ν = 1731 (C═O) cm.sup.-1.             IIb.48                                                                              (CH.sub.2).sub.2 CO.sub.2 C.sub.2 H.sub.5                                                   C.sub.20 H.sub.26 O.sub.2 (298,43); MS: m/e = 298                             (M.sup.⊕,                                                                 100%); IR: - ν = 1730 (C═O) cm.sup.-1.             IIb.49                                                                              (CH.sub.2).sub.2 CO.sub.2 iC.sub.3 H.sub.7                                                  C.sub.21 H.sub.28 O.sub.2 (312,45); MS: m/e = 312                             (M.sup.⊕,                                                                 100%); IR: - ν = 1731 (C═O) cm.sup.-1.             IIb.50                                                                              (CH.sub.2 ).sub.2 CO.sub.2 C.sub.4 H.sub.9                                                  C.sub.22 H.sub.30 O.sub.2 (326,48); MS: m/e = 326                             (M.sup.⊕,                                                                 100%); IR: - ν = 1730 (C═O) cm.sup.-1.             IIa.51                                                                              (CH.sub.2).sub.3 OH                                                                         C.sub.18 H.sub.24 O.sub.2 (256,39); MS: m/e = 256                             (M.sup.⊕)                                                                 241, 238, 225, 183;                                                           IR: - ν = 1731 (C═O) cm.sup.-1.                    IIa.52                                                                              (CH.sub.2).sub.4 CO.sub.2 H                                                                 C.sub.20 H.sub.26 O.sub.2 (298,43); MS: m/e = 298                             (M.sup.⊕,                                                                 100%); IR: - ν = 1703 (C═O) cm.sup.-1.             IIa.53                                                                              (CH.sub.2).sub.4 CO.sub.2 CH.sub.3                                                          C.sub.21 H.sub.28 O.sub.2 (312,45); MS: m/e = 312                             (M.sup.⊕,                                                                 100%); IR: - ν = 1731 (C═O) cm.sup.-1.             IIa.54                                                                              (CH.sub.2).sub.5 CO.sub.2 H                                                                 C.sub.21 H.sub.28 O.sub.2 (312,45); MS: m/e =  312                            (M.sup.⊕,                                                                 100%); IR: - ν = 1699 (C═O) cm.sup.-1.             IIa.55                                                                              (CH.sub.2).sub.5 CO.sub.2 CH.sub.3                                                          C.sub.22 H.sub.30 O.sub.2 (326,48); MS: m/e = 326                             (M.sup.⊕,                                                                 60%); IR: - ν = 1730 (C═O) cm.sup.-1.              IIa.56                                                                              (CH.sub.2).sub.9 CO.sub.2 H                                                                 C.sub.26 H.sub.40 O.sub.2 (384,61);                                           MS: m/e = 384 (M.sup.⊕);                                                  IR: - ν = 1695 (C═O) cm.sup.-1.                    IIa.57                                                                              (CH.sub.2).sub.9 CO.sub.2 CH.sub.3                                                          C.sub.27 H.sub.42 O.sub.2 (398,63);                                           MS: m/e = 398 (M.sup.⊕);                                                  IR: - ν = 1733 (C═O) cm.sup.-1.                    __________________________________________________________________________     .sup.1) HW: HoubenWeyl: Methoden der organ. Chemie, vol. 5; part 2c,          Thieme Verlag Stuttgart, New York 1985.                                  

B) Preparation of azulenesquaric acid dyes

EXAMPLE 13 Guaiazulene(2-(methoxycarbonyl)ethyl)squaric acid dye (Ib.38)

13.5 g (0.05 mol) of methyl guaiazulenepropionate (Example 2) and 5.8 g(0.05 mol) of squaric acid were refluxed in 600 ml of 1:1toluene/n-butanol for 8 hours under a water separator. The solvent wasthen distilled off. The green oil was taken up with a little methylenechloride and purified by column chromatography (1 kg of silica gel; 9:1methylene chloride/acetone).

Yield: 10.1 g (65%); mp.: 175°-177° C;

UV (toluene): λ max=773 nm, ε=112100;

UV (CH₂ Cl₂): λ max=768 nm, ε=112700;

UV (CH₂ H₅ OH): λ max=759 nm, ε=115300;

IR (KBr): ν=2960, 2870, 1731 (C=O), 1611, 1548, 1435, 1385, 1330 s 1247,1178, 1075, 1011, 899 cm⁻¹ ; ¹ H-NMR (CDCl₃): σ=1.35 d(12H), 2.55 s(6H),2.70 t(4H), 3.12 q(2H), 3.50 s(6H), 4.27 t(4H), 7.57 d(2H), 7.62 d(2H),8.10 s(2H), 8.89 s(2H); ¹³ C-NMR (CDCl₃): σ=13.03, 24.18 (2C), 34.73,35.28, 38.26, 51.47, 121.19, 130.85, 134.19, 134.69, 138.22, 139.77,141.55, 147.68, 150.65, 154.33, 172.93, 181.36, 183.19; MS: m/e=618(M.sup.⊕, 2%).

EXAMPLE 14 Guaiazulene(2-(Isopropoxycarbonyl)Ethyl)Squaric Acid Dye(Ib.41) Method of Preparation 1

2.5 g (8.4 mmol) of isopropylguaiazulenepropionate (IIb.41) and 1.14 g(10 mmol) of squaric acid were boiled for 8 hours in 80 ml of tolueneand 80 ml of n-butanol under a water separator, the solvent was thendistilled off, and the residue was chromatographed over silica gel.

Yield: 1.6 g (56.5%); mp.: 126°-127° C.;

UV (CH₂ Cl₂): λmax=769 nm, ε=113550;

IR: ν=2958, 1724 (C=O), 1611, 1431, 1387, 1327s, 1247, 1180, 1010, 960,898, 800 cm°¹ ; ¹ H-NMR (CDCl₃): δ=1.03 d(12H), 1.38 d(12H), 2.54 s(6H),2.65 t(4H), 3.12 q(2H), 4.29 t(4H), 4.82 q(2H), 7.57 d(d), (4H), 8.20s(2H), 8.90 s(2H); ¹³ C-NMR (CDCl₃): δ=12.96, 21.69 (2C), 24.22 (2C),34.96, 36.00, 38.37, 67.57, 121.55, 130.76, 134.00, 134.56, 138.01,140.01, 141.83, 147.80, 150.42, 154.84, 172.02, 182.06, 183.10; Ms:m/e=674 (M.sup.⊕, 15%).

EXAMPLE 15 Guaiazulene(2-(Isopropoxycarbonyl)Ethyl)Squaric Acid Dye(Ib..41) Method of Preparation 2

5.13 g (0.02 mmol) of guaiazulenepropionic acid (Example 1) and 3.4 g(0.03 mmol) of squaric acid were refluxed for 12 hours in 250 ml oftoluene and 250 ml of isopropanol under a water separator, the solventwas then distilled off, and the residue was chromatographed over silicagel.

According to DC, IR and ¹ H-NMR the product is identical to the productof Example 14, but has a slightly lower melting point which may be dueto residues (<1%) of free carboxylic acid groups on the dye.

Yield: 2.6 g (38.5%); mp.: 120°-121° C.;

UV (CH₂ Cl₂): λ max=769 nm, ε=111950.

EXAMPLE 16 Bis[n-butyl3-(7-Isopropyl-1-Methyl)Azulen-4-yl-2-Ethylpropionate]Squaric Acid Dye(Compound No. 10)

17.0 g (0.05 mol) of butylazulene-7-isopropyl-1-methyl-4-α-ethylpropionate (Example 7) and 11.4 g(0.1 mol) of squaric acid were refluxed for 1 hour in 1,000 ml of 1:1toluene/n-butanol. The green oil remaining on distilling off the solventwas taken up in a little methylene chloride and chromatographed oversilica gel (9:1 methylene chloride/acetone) giving 10.9 g (54%) of dyeNo. 10 in the form of reddish brown crystals of mp. 154° C.

Physical data:

UV (CH₂ Cl₂): λ_(max) =771 mm (ε=113525);

IR (KBr): ν=2959, 2928, 2870 (CH); 1728 (C=O); 1610, 1596, 1432, 1384,1330s, 1250, 1223, 1181, 1033, 1004 cm⁻¹ ;

¹ H-NMR (CDCl₃): δ=0.78 m(12H), 1.06 me(4H), 1.25 mc(4H), 1.48 d(12H),1.58 m(4H), 2.53 s(6H), 2.58 m(2H), 3.08 me (2H), 3.72 m(4H), 3.78m(2H), 4.62 mc(2H), 7.45, 7.55 AB(4H), 8.06s (2H), 8.85 s(2H);

¹³ C-NMR (CDCl₃): δ=11.89 (2C), 12.94 (2C), 13.58 (2C), 19.05 (2C),24.22 (4C), 26.02 (2C), 30.63 (2C), 38.38 (2C), 42.43 (2C), 49.68 (2C),63.90 (2C), 121.78 (2C), 130.49 (2C), 133.85 (2C), 134.90 (2C), 137.80(2C), 139.74 (2C), 142.24 (2C), 147.62 (2C), 150.32 (2C), 153.93 (2C),174.84 (2C), 181.76 (2C), 183.16 (2C);

MS: m/e=758 (100%), 759-762 (M.sup.⊕ ⊕-Isotope peaks).

The same method was used to prepare the azulene-squaric acid dyes listedin Table 3. The structure of these dyes was confirmed by ¹ H-NMR, ¹³C-NMR, IR and MS spectra.

    TABLE 3      ##STR48##       Compound      λmax [nm] mp. No. R.sup.1 R.sup.2 R.sup.3 R.sup.4     R.sup.5 (in CH.sub.2      Cl.sub.2) [°C.]                                1 CH.sub.2     CO.sub.2 sC.sub.4 H.sub.9 H CH(CH.sub.3).sub.2 H CH.sub.3 767 108-110  2      ##STR49##      H CH(CH.sub.3).sub.2 H CH.sub.3 767 [oil]*  3 CH.sub.2 CO.sub.2     CH.sub.2 CH.sub.2 Br H CH(CH.sub.3).sub.2 H CH.sub.3 767 130-132  4      ##STR50##      H CH(CH.sub.3).sub.2 H CH.sub.3 768 220-221      5     ##STR51##      H CH(CH.sub.3).sub.2 H CH.sub.3 770 172-173      6     ##STR52##      H CH(CH.sub.3).sub.2 H CH.sub.3 768 196-197      7     ##STR53##      H CH(CH.sub.3).sub.2 H CH.sub.3 770 185-187      8     ##STR54##      H CH(CH.sub.3).sub.2 H CH.sub.3 773 194      9     ##STR55##      H CH(CH.sub.3).sub.2 H CH.sub.3 771 180-182      10     ##STR56##      H CH(CH.sub.3).sub.2 H CH.sub.3 771(see Ex. 16) 154      11     ##STR57##      H CH(CH.sub.3).sub.2 H CH.sub.3 773 181      12     ##STR58##      H CH(CH.sub.3).sub.2 H CH.sub.3 768 215-217  13 CH.sub.2 OC(O)CH.sub.3     H CH(CH.sub.3).sub.2 H CH.sub.3 765 [oil]* 14 (CH.sub.2).sub.2      OC(O)CH.sub.3 H CH(CH.sub.3).sub.2 H CH.sub.3 765 [oil]* 15 (CH.sub.2).s     ub.2 OC(O)C(CH.sub.3).sub.3 H CH(CH.sub.3).sub.2 H CH.sub.3 768 >80* 16     (CH.sub.2).sub.2 OC(O)C.sub.9 H.sub.19 H CH(CH.sub.3).sub.2 H CH.sub.3     765 [oil]*      17     ##STR59##      H CH(CH.sub.3).sub.2 H CH.sub.3 765 [oil]*      18     ##STR60##      H CH(CH.sub.3).sub.2 H CH.sub.3 768 230-232      19     ##STR61##      H CH(CH.sub.3).sub.2 H CH.sub.3 767 183-185      20     ##STR62##      H CH(CH.sub.3).sub.2 H CH.sub.3 769 208-209      21     ##STR63##      H CH(CH.sub.3).sub.2 H CH.sub.3 772 [oil]*      22     ##STR64##      H CH(CH.sub.3).sub.2 H CH.sub.3 772 201-202*      23     ##STR65##      H CH(CH.sub.3).sub.2 H CH.sub.3 770 [oil]*  24 (CH.sub.2).sub.2     OCH.sub.3 H CH.sub.3 H CH.sub.3 763 [oil]* 25 CO.sub.2 C.sub.2 H.sub.5     CH.sub.3 H CH.sub.3 H 723 155-162* 26 CO.sub.2 nC.sub.3 H.sub.7 CH.sub.3     H CH.sub.3 H 721 [oil]* 27 CO.sub.2 iC.sub.3 H.sub.7 CH.sub.3 H CH.sub.3     H 723 136-140* 28 H CH.sub.3 H CH.sub.3 CH(CH.sub.3).sub.2 744 ca. 255*     29 H CH.sub.3 H CH.sub.3      ##STR66##      756 177-179      30 H CH.sub.3 H CH.sub.3     ##STR67##      757 145-148      31 H CH.sub.3 H CH.sub.3     ##STR68##      739 [oil]*      32 H CH.sub.3 H CH.sub.3     ##STR69##      746 [oil]*      33 H CH.sub.3 H CH.sub.3     ##STR70##      746 [oil]*      34 H CH.sub.3 H CH.sub.3     ##STR71##      749 [oil]*      35 H CH.sub.3 H CH.sub.3     ##STR72##      723 ca. 280*      36 H CH.sub.3 H CH.sub.3     ##STR73##      739 230-232      37 H CH.sub.3 H CH.sub.3     ##STR74##      734 >160*      38 H CH.sub.3 H CH.sub.3     ##STR75##      749 277-279      39 H CH.sub.3 H CH.sub.3     ##STR76##      747 230-231      40 H     ##STR77##      H CH.sub.3 H 728 268      41 H     ##STR78##      H      ##STR79##      H 746 237     (*denotes that the product is either an isomeric mixture or not     analytically pure)

                                      TABLE 4                                     __________________________________________________________________________    List of azulenesquaric acid dyes I                                            Compound                                                                      No.   R.sup.1       Comments: characterization                                __________________________________________________________________________    Ia.1  H             (Reference) cf. W. Ziegenbein and                                             H. -E. Sprenger, Angew. Chem., 78,                                            (1966), 937; C.sub.30 H.sub.26 O.sub.2 (418,54)                               λmax = 720 nm (CHCl.sub.3),                                            MS: m/e = 418 (M.sup.⊕, 100%).                        Ia.2  CH.sub.3      C.sub.32 H.sub.30 O.sub.2 (446,59); λmax = 718                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 446 (M.sup.⊕,                              100%).                                                    Ia.3  CH(CH.sub.3).sub.2                                                                          C.sub.36 H.sub.38 O.sub.2 (502,70); λmax = 720                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 502 (M.sup.⊕,                              100%).                                                    Ia.4  C.sub.4 H.sub.9                                                                             C.sub.38 H.sub.42 O.sub.2 (530,75); λmax = 715                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 530 (M.sup.⊕,                              100%).                                                    Ia.5  CH.sub.2 --C.sub.6 H.sub.5                                                                  C.sub.44 H.sub.38 O.sub.2 (598,79); λmax = 719                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 598 (M.sup.⊕,                              80%),                                                                         91 (100%).                                                Ia.6  CO.sub.2 H    C.sub.32 H.sub.26 O.sub.6 (506,56); λmax = 720                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 506 (M.sup.⊕,                              10%).                                                     Ia.7  CO.sub.2 CH.sub.3                                                                           C.sub.34 H.sub.30 O.sub.6 (534,61); λmax = 720                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 534 (M.sup.⊕,                              1%);                                                                          IR: - ν = 1731 cm.sup.-1 (C═O).                    Ia.8  CO.sub.2 C.sub.4 H.sub.9                                                                    C.sub.40 H.sub.42 O.sub.6 (618,77); λmax = 718                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 618 (M.sup.⊕,                              0,5%);                                                                        IR: - ν = 1732 cm.sup.-1 (C═O).                    Ia.9  CH.sub.2 CO.sub.2 H                                                                         C.sub.34 H.sub.30 O.sub.6 (534,61); λmax = 718                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e =  534 (M.sup.⊕);                            IR: - ν = 1698 cm.sup.-1 (C═O).                    Ia.10 CH.sub.2 CO.sub.2 CH.sub.3                                                                  C.sub.36 H.sub.36 O.sub.6 (562,66); λmax = 722                         nm                                                                            (CH.sub.2 Cl.sub.2), 713 nm (C.sub.2 H.sub.5 OH);                             MS: m/e = 562 (M.sup.⊕, 3%);                                              IR: - ν = 1731 (C═O), 1609, 1578, 1434,                                1389, 1302s, 1209, 1162, 1104, 970,                                           718 cm.sup.-1.                                            Ia.11 CH.sub.2 CO.sub.2 C.sub.2 H.sub.5                                                           C.sub.38 H.sub.40 O.sub.6 (592,73); λmax = 718                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 592 (M.sup.⊕,                              4%);                                                                          IR: - ν = 1730 (C═O), 1300 cm.sup.-1.              Ia.12 CH.sub.2 CO.sub.2 -n-C.sub.3 H.sub.7                                                        C.sub.40 H.sub.44 O.sub.6 (620,79); λmax = 720                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 620 (M.sup.⊕ ,                             3%);                                                                          IR: - ν = 1729 (C═O), 1298 cm.sup.-1.              Ia.13 CH.sub.2 CO.sub.2 -i-C.sub.3 H.sub.7                                                        C.sub.40 H.sub.44 O.sub.6 (620,79); λmax = 721                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 620 (M.sup.⊕,                              0,5%);                                                                        IR: - ν = 1733 (C═O), 1303 cm.sup.-1.              Ia.14 CH.sub.2 CO.sub.2 C.sub.4 H.sub.9                                                           C.sub.42 H.sub.48 O.sub.6 (648,84); λmax = 720                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 648 (M.sup.⊕,                              1%);                                                                          IR: - ν = 1730 (C═O), 1301 cm.sup.-1.              Ia.15 CH.sub.2 CO.sub.2 C.sub.8 H.sub.17                                                          C.sub.50 H.sub.64 O.sub.6 (761,06);                                           λmax = 720 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1731 (C═O), 1302 cm.sup.-1.              Ia.16 (CH.sub.2).sub.2 OH                                                     Ia.17 (CH.sub.2).sub.2 CO.sub. 2 H                                                                C.sub.36 H.sub.34 O.sub.6 (562,66); λmax = 716                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 562 (M.sup.⊕,                              1%);                                                                          IR: - ν = 1702 cm.sup.-1.                              Ia.18 (CH.sub.2).sub.2 CO.sub.2 CH.sub.3                                                          C.sub.38 H.sub.38 O.sub.6 (590,72); λmax = 719                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 590 (M.sup.⊕,                              2%);                                                                          IR: - ν = 1733 (C═O), 1301s cm.sup.-1.             Ia.19 (CH.sub.2).sub.2 CO.sub.2 C.sub.2 H.sub.5                                                   C.sub.40 H.sub.42 O.sub.6 (618,77); λmax = 721                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 618 (M.sup.⊕,                              1%);                                                                          IR: - ν = 1730 (C═O), 1606, 1437, 1390,                                1304s, 1210, 1166, 1074, 1034, 971,                                           720 cm.sup.-1.                                                                .sup.13 C-NMR (CDCl.sub.3): δ = 14,22, 28,15,                           29,00, 34,39, 35,45, 60,70, 119,76,                                           124,65, 134,05, 134,77, 136,18,                                               137,59, 140,84, 146,00, 149,68,                                               150,01, 153,70, 172,09, 182,68.                           Ia.20 (CH.sub.2).sub.2 CO.sub.2 iC.sub.3 H.sub.7                                                  C.sub.42 H.sub.46 O.sub.6 (646,83);                                           λmax = 722 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1733 (C═O), 1300s cm.sup.-1.             Ia.21 (CH.sub.2).sub.2 CO.sub.2 C.sub.4 H.sub.9                                                   C.sub.44 H.sub.50 O.sub.6 (674,88);                                           λmax = 720 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1731 (C═O), 1301s cm.sup.-1.             Ia.22 (CH.sub.2).sub.3 OH                                                                         no product by Example 9                                   Ia.23 (CH.sub.2).sub.4 CO.sub.2 H                                                                 C.sub.40 H.sub.42 O.sub.6 (618,77);                                           λmax = 717 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1704 (C═O) cm.sup.-1.                    Ia.24 (CH.sub.2).sub.4 CO.sub.2 CH.sub.3                                                          C.sub.42 H.sub.46 O.sub.6 (646,83);                                           λmax = 724 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1733 (C═O), 1298s cm.sup.-1.             Ia.25 (CH.sub.2).sub.5 CO.sub.2 H                                                                 C.sub.42 H.sub.46 O.sub.6 (646,83);                                           λmax = 718 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1701 (C═O) cm.sup.-1.                    Ia.26 (CH.sub.2).sub.5 CO.sub.2 CH.sub.3                                                          C.sub.44 H.sub.50 O.sub.6 (674,88);                                           λmax = 722 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1730 (C═O), 1301s cm.sup.-1.             Ia.27 (CH.sub.2).sub.9 CO.sub.2 H                                                                 C.sub.50 H.sub.62 O.sub.6 (759,04);                                           λmax = 719 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1698 (C═O) cm.sup.-1.                    Ia.28 (CH.sub.2).sub.9 CO.sub.2 CH.sub.3                                                          C.sub.52 H.sub.66 O.sub.6 (787,10);                                           λmax = 725 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1732 (C═O), 1302s cm.sup.-1.             Ib.29 H             (Reference)                                                                   cf. W. Ziegenbein and H. -E. Sprenger,                                        Angew. Chem., 78, (1966), 937;                                                mp.: 256-57° C. (dec.);                                                λmax = 767 nm, ε = 133500                                      (CHCl.sub.3);                                                                 C.sub.34 H.sub.34 O.sub.2 (474,65); MS: m/e = 474                             (M.sup.⊕,                                                                 100%), 459 (M.sup.⊕ -CH.sub.3), 431, 209, 43;                             IR(KBr): - ν = 2980, 1610, 1585, 1420,                                     1384s, 1328s, 1297sh, 1238, 1213,                                             1180, 1087, 1006, 957, 897, 873, 839,                                         799, 645, 585 cm.sup.-1 ;                                                     .sup.1 H-NMR (CDCl.sub.3): σ = 1,36 d(6H),                              2,51                                                                          s(3H), 3,11 g(1H), 3,38 s(3H), 7,48                                           d(d)(2H), 8,07 s(1H), 8,77 s(1H);                                             .sup.13 C-NMR (CDCl.sub.3): σ = 12,92, 24,33,                           28,10, 38,31, 121,85, 130,46, 133,96,                                         135,50, 137,70, 139,09, 142,42,                                               147,09, 149,92, 152,60, 182,75,                                               183,46.                                                   Ib.30 CH.sub.3      C.sub.36 H.sub.38 O.sub.2 (502,70); λmax = 766                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 502 (M.sup.⊕,                              100%).                                                    Ib.31 CH(CH.sub.3).sub.2                                                                          C.sub.40 H.sub.46 O.sub.2 (558,81); λmax = 769                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 558 (M.sup.⊕,                              100%),                                                                        543, 528.                                                 Ib.32 C.sub.4 H.sub.9                                                                             C.sub.42 H.sub.50 O.sub.2 (586,86); λmax = 767                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 586 (M.sup.⊕,                              100%).                                                    Ib.33 CH.sub.2 --C.sub.6 H.sub.5                                                                  C.sub.48 H.sub.46 O.sub.2 (654,90); λmax = 769                         nm,                                                                           (CH.sub.2 Cl.sub.2); MS: m/e = 654 (M.sup.⊕,                              40%),                                                                         91 (C.sub.7 H.sub.7.sup.⊕, 100%);                                         .sup.1 H-NMR (CDCl.sub.3): σ = 1,35 d(12H),                             2,54                                                                          s(6H), 2,76 t(4H), 3,09 q(2H), 4,13                                           t(4H), 6,90 m(4H,Phenyl), 7,03 m(6H,                                          Phenyl), 7,37 d(2H), 7,52 d(2H),                                              8,08 s(2H), 8,70 s(2H).                                   Ib.34 CO.sub.2 H    C.sub.36 H.sub.34 O.sub.6 (562,66); λmax = 760                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 562 (M.sup.⊕,                              10%).                                                                         IR: - ν = 1698 (C═O) cm.sup.-1.                    Ib.35 CO.sub.2 CH.sub.3                                                                           C.sub.38 H.sub.38 O.sub.6 (590,72); λmax = 767                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 590 (M.sup.⊕,                              100%);                                                                        IR: - ν = 1732 (C═O) cm.sup.-1.                    Ib.36 CO.sub.2 C.sub.4 H.sub.9                                                                    C.sub.44 H.sub.50 O.sub.6 (674,88); λmax = 769                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 674 (M.sup.⊕),                             101,                                                                          73, 57.                                                                       IR: - ν = 1732 (C═O) cm.sup.-1.                    Ib.37 CH.sub.2 CO.sub.2 H                                                                         C.sub.38 H.sub.38 O.sub.6 (590,72); λmax = 768                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 590 (M.sup.⊕,                              4%);                                                                          IR: - ν = 1701 (C═O) cm.sup.-1.                    Ib.38 CH.sub.2 CO.sub.2 CH.sub.3                                                                  see Example 13                                            Ib.39 CH.sub.2 CO.sub.2 C.sub.2 H.sub.5                                                           C.sub.42 H.sub.46 O.sub.6 (646,83); mp.:                                      138-140° C.                                                            λmax = 768 nm (CH.sub.2 Cl.sub.2),                                     MS: m/e = 646 (M.sup.⊕, 100%), 631, 617,                                  601, 573, 500, 73, 45.                                                        .sup.1 H-NMR (CDCl.sub.3): δ = 1,07 t(6H),                              1,39                                                                          d(12H), 2,56 s(6H), 2,68 t(4H), 3,12                                          q(2H), 3,95 q(4H), 4,28 t(4H), 7,58                                           d(d) [4H], 8,10 s(2H), 8,90 s(2H);                                            IR: - ν = 1725 (C═O), 1611, 1434, 1384,                                1321s, 1248, 1181, 1074, 1009, 899,                                           801, 598 cm.sup.-1.                                       Ib.40 CH.sub.2 CO.sub.2 -n-C.sub.3 H.sub.7                                                        C.sub.44 H.sub.50 O.sub.6 (674,88); λmax = 768                         nm                                                                            (CH.sub.2 Cl.sub.2), MS: m/e = 674 (M.sup.⊕,                              0.8%);                                                                        mp.: 141-146° C.;                                                      IR: - ν = 2962, 1724 (C═O), 1610, 1457,                                1434, 1384, 1333, 1323s, 1250, 1074,                                          1011, 900, 804, 609 cm.sup.-1 ;                                               .sup.1 H-NMR (CDCl.sub.3): δ = 0.76 t(6H),                              1,39                                                                          d(12H), 1,43 h(4H), 2,56 s(6H), 2,69                                          t(4H), 3,11 q(2H), 3,86 t(4H), 4,30                                           t(4H), 7,58 d(d)(4H), 8,10 s(2H),                                             8,90 s(2H);                                                                   .sup.13 C-NMR (CDCl.sub.3): δ = 10,26, 12,97,                           21,94, 24,21 (2C), 34,95, 35,63,                                              38,35, 65,98, 121,48, 130,79, 134,06,                                         134,59, 138,08, 139,99, 141,75,                                               147,79, 150,50, 172,60, 181,93,                                               183,12                                                    Ib.41 CH.sub.2 CO.sub.2 -i-C.sub.3 H.sub.7                                                        C.sub.44 H.sub.50 O.sub.6 (674,88);                                           see Examples 14 and 15                                    Ib.42 CH.sub.2 CO.sub.2 C.sub.4 H.sub.9                                                           C.sub.46 H.sub.54 O.sub.6 (702,93); λmax = 767                         nm                                                                            (CH.sub.2 Cl.sub.2), 760 nm (C.sub.2 H.sub.5 OH);                             MS: m/e = 702 (M.sup.⊕), 312, 101, 73,                                    57, 55 (100%);                                                                IR: - ν = 2956, 2928, 2856, 1736 (C═O),                                1609, 1461, 1386, 1339s, 1258,                                                1057 cm.sup.-1.                                           Ib.43 CH.sub.2 CO.sub.2 C.sub.8 H.sub.17                                                          C.sub.54 H.sub.70 O.sub.6 (815,15);                                           λmax = 767 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1731 (C═O), 1330s cm.sup.-1.             Ib.44 CH.sub.2 CO.sub.2 [(CH.sub.2).sub.2 O].sub.2 C.sub.2 H.sub.5                                C.sub.50 H.sub.62 O.sub.10 (823,04);                                          λmax = 770 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1732 (C═O), 1329, 1180 cm.sup.-1.        Ib.45 (CH.sub.2).sub.3 OH                                                     Ib.46 (CH.sub.2).sub.2 CO.sub.2 H                                                                 C.sub.40 H.sub.42 O.sub.6 (618,77);                                           λmax = 765 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1699 (C═O) cm.sup.-1.                    Ib.47 (CH.sub.2).sub.2 CO.sub.2 CH.sub.3                                                          C.sub.42 H.sub.46 O.sub.6 (646,83); λmax = 767                         nm,                                                                           (CHCl.sub.2), 760 nm (C.sub.2 H.sub.5 OH);                                    MS: m/e = 646 (M.sup.⊕, 30%);                                             IR: - ν = 2960, 1731 (C═O), 1611, 1433,                                1386, 1330s, 1246, 1081, 1012, 901.                                           578 cm.sup.-1 ;                                                               .sup.1 H-NMR (CDCl.sub.3): σ = 1,35 d(2H),                              1,94                                                                          q(4H), 2,21 t(4H), 2,55 s(6H), 3,10                                           q(2H), 3,55 s(6H), 3,96 t(4H), 7,55                                           d(d)[4H,Azul.], 8,10 s(2H,Azul.),                                             8,87 s(2H,Azul.);                                                             .sup.13 C-NMR (CDCl.sub.3): σ = 12,95, 24,20,                           (2C), 27,03, 33,48, 38,33, 38,91,                                             51,28, 121,63, 130,81, 133,86,                                                134,41, 138,22, 139,92, 141,98,                                               147,49, 150,26, 155,79, 173,46,                                               181,88, 183,05.                                           Ib.48 (CH.sub.2).sub.2 CO.sub.2 C.sub.2 H.sub.5                                                   C.sub.44 H.sub.50 O.sub.6 (674,88);                                           λmax = 768 nm (CH.sub.2 Cl.sub. 2),                                    MS: m/e = 674 (M.sup.⊕);                                                  IR: - ν = 1732 (C═O), 1330s cm.sup.-1.             Ib.49 (CH.sub.2).sub.2 CO.sub.2 iC.sub.2 H.sub.5                                                  C.sub.46 H.sub.54 O.sub.6 (702,93);                                           λmax = 767 nm (CH.sub.2 Cl.sub.2),                                     MS: m/e = 702 (M.sup.⊕);                                                  IR: - ν = 1730 (C═O), 1330s cm.sup.-1.             Ib.50 (CH.sub.2).sub.2 CO.sub.2 C.sub.4 H.sub.9                                                   C.sub.48 H.sub.58 O.sub.6 (730,99);                                           λmax = 768 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 2960, 1720 (C═O), 1611s,                                     1433, 1388, 1336s, 1296, 1252s,                                               1225, 1048, 1015, 991, 907, 801,                                              610 cm.sup.-1 ;                                                               .sup.1 H-NMR (CDCl.sub.3): δ = 0,88 t(6H),                              1,32                                                                          q(4H), 1,41 d(12H), 1,53 q(4H), 1,92                                          q(4H), 2,19 t(4H), 2,57 s(6H), 3,14                                           q(2H), 3,90 t(4H), 3,98 t(4H), 7,57                                           d(d), (4H), 8,12 s(2H), 8,84 s(2H);                                           .sup.13 C-NMR (CDCl.sub.3): δ = 13,05, 13,69,                           19,07, 24,24 (2C), 27,03, 30,58,                                              33,53, 38,32, 38,76, 64,18, 121,28,                                           130,72, 133,86, 134,42, 138,23,                                               139,49, 139,55, 141,81, 147,29,                                               150,25, 155,60, 173,26, 180,72,                                               183,14.                                                   Ib.52 (CH.sub.2).sub.4 CO.sub.2 H                                                                 C.sub.44 H.sub.50 O.sub.6 (674,88);                                           λmax = 765 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1703 (C═O) cm.sup.-1.                    Ib.53 (CH.sub.2).sub.4 CO.sub.2 CH.sub.3                                                          C.sub.46 H.sub.54 O.sub.6 (702,93);                                           λmax = 768 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1733 (C═O), 1331s cm.sup.-1.             Ib.54 (CH.sub.2).sub.5 CO.sub.2 H                                                                 C.sub.46 H.sub.54 O.sub.6 (702,93);                                           λmax = 764 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1702 (C═O) cm.sup. -1.                   Ib.55 (CH.sub.2).sub.5 CO.sub.2 CH.sub.3                                                          C.sub.48 H.sub.58 O.sub.6 (730,99);                                           λmax = 767 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1732 (C═O), 1330s cm.sup.-1.             Ib.56 (CH.sub.2).sub.9 CO.sub.2 H                                                                 C.sub.54 H.sub.70 O.sub.6 (815,15);                                           λmax = 766 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1705 (C═O) cm.sup.-1.                    Ib.57 (CH.sub.2).sub.9 CO.sub.2 CH.sub.3                                                          C.sub.56 H.sub.74 O.sub.6 (843,20);                                           λmax = 770 nm (CH.sub.2 Cl.sub.2),                                     IR: - ν = 1731 (C═O), 1331s cm.sup.-1.             __________________________________________________________________________

C) Production of optical recording media

EXAMPLE 17

A 5% strength by weight solution of dye Ib.42 in toluene was appliedwith a syringe to a rotating polymethyl methacrylate disk at about 2,000rpm, and the residual solvent was then spun off at 5,000 rpm. The resultobtained was homogeneous, highly reflective dye layer which wasexcellently writable with a semiconductor laser (λ=830 nm). The data canbe read back with good contrast.

EXAMPLE 18

A 3% strength by weight solution of dye Ib.41 containing 30% by weight,based on the solids content of the solution, of polymethyl methacrylatewas spincoated by the method of Example 17 onto a grooved polycarbonatedisk. The result obtained was a homogeneous, highly reflective dye layerwhich was firmly adherent to the substrate, gave a good image of thetracking grooves on the substrate and was excellently writable with asemiconductor laser (λ=830 nm). The written information was stable inthe conditioning test and can be read back as often as desired.

EXAMPLE 19

A 2% strength by weight solution of dye Ib.38 containing, based on thesolids content of the solution, 30% by weight of polymethyl methacrylateas a binder and 5% by weight of4-octyl-4'-fluorobiphenyldithiolenenickel as a stabilizer was spincoatedonto a grooved polycarbonate disk as described in Example 17. Thestorage layer obtained was similar to that of Example 11 in all respectsbut had an increased stability to UV light.

EXAMPLE 20

A 2% strength by weight solution of dye Ib.10 in 1:1 propanol/diacetonealcohol containing, based on the solids content of the solution, 30% byweight of polymethyl methacrylate and 5% by weight ofbiscampheratodithiolenenickel was spincoated onto a glass disk asdescribed in Example 17. The dye layer obtained was homogeneous andshowed high background reflectivity. It was readily writable with asemiconductor laser (λ=780 nm). The written data were stable under thecustomary test conditions and can be read back as often as desired.

EXAMPLE 21

A 5% strength by weight solution of dye 10 in toluene was applied with asyringe to a rotating polymethyl methacrylate disk at about 2,000 rpm,and the remaining solvent was then spun off at 5,000 rpm. The resultobtained was a homogeneous, highly reflective dye layer which wasexcellently writable with a semiconductor laser (λ=830 nm). The data canbe read back with good contrast.

EXAMPLE 22

A 3% strength by weight solution of dye 10 in propanol/diacetonealcohol, containing 30% by weight, based on the solids content of thesolution, of MMA/MAS copolymer was spuncoated onto a groovedpolycarbonate disk as described in Example 17. The result obtained was ahomogeneous, highly reflective dye layer which was firmly adherent tothe substrate, gave a good image of the tracking grooves on thesubstrate and was excellently writable with a semiconductor laser (λ=830nm). The written information was stable in the conditioning test and canbe read back as often as desired with good contrast.

EXAMPLE 23

A 2% strength by weight solution of dye 10 containing, based on thesolids content of the solution, 30% by weight of polymethyl methacrylateas a binder and 5% by weight of4-octyl-4'-fluorobiphenyldithiolenenickel as a stabilizer was spuncoatedonto a grooved polycarbonate disk as described in Example 17. Thestorage layer obtained was similar to that of Example 17 in all respectsbut had an increased stability to UV light.

EXAMPLE 24

A 2% strength by weight solution of Dye 22 in a 1:1 propanol/diacetonealcohol containing, based on the solids content of the solution, 30% byweight of polymethyl methacrylate and 5% by weight ofbiscampheratodithiolenenickel was spuncoated onto a glass disk asdescribed in Example 17. The dye layer obtained was homogeneous and hada high background reflectivity. It was readily writable with asemiconductor laser (λ=780 nm). The written data were stable under thecustomary test conditions and can be read back as often as desired.

We claim:
 1. An azulenesquaric acid dye of the formula I ##STR80## whereR¹ is carboxyl, C₁ -C₁₂ -alkoxycarbonyl, C₁ -C₁₂ -alkoxycarbonyl wherethe alkyl chain is interrupted by one or more oxygen atoms, carbamoyl,C₁ -C₄ -monoalkyl- or -dialkylcarbamoyl or C₁ -C₁₂ -alkyl, which issubstituted by halogen, amino, hydroxyl, C₁ -C₁₂ -alkoxy, phenyl, phenylsubstituted by C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy, C₁ -C₄ -dialkylamino,N-phenyl-N-(C₁ -C₄ -alkyl)amino or halogen, carboxyl, C₁ -C₁₂-alkoxycarbonyl, C₁ -C₁₂ -haloalkoxycarbonyl, C₁ -C₁₂-phenylalkoxycarbonyl, cyano, C₁ -C₁₂ -alkanoyloxy, benzoyloxy,benzoyloxy substituted by dimethoxy-methyl, and/or by the radial##STR81## where R⁶ and R⁷ are identical or different and each is C₁ -C₄-alkyl or phenyl independently of the other, and R², R³, R⁴ and R⁵ areidentical or different and each is hydrogen or C₁ -C₁₂ -alkyl, C₁ -C₁₂-alkyl substituted by halogen, amino, C₁ -C₁₂ -alkoxy, phenyl, phenylsubstituted by C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy, C₁ -C₄ -dialkylamino,N-phenyl-N-(C₁ -C₄ -alkyl)amino or halogen, carboxyl, C₁ -C₁₂-alkoxycarbonyl or cyano, independently of the others, with the provisothat, when R⁵ is hydrogen, the positions of substituents CH₂ -R¹ and R⁴on either or both azulene rings may also be interchanged within anazulene ring.
 2. An azulenesquaric acid dye as claimed in claim 1,wherein R², R³, R⁴ and R⁵ are each C₁ -C₆ -alkyl.
 3. An azulenesquaricacid dye as claimed in claim 1, wherein R² and R⁴ are each methyl and R³and R⁵ are each hydrogen.
 4. An azulenesquaric acid dye as claimed inclaim 1, wherein R² and R⁴ are each hydrogen, R³ is isopropyl and R⁵ ismethyl.